1. Field of the Invention
The present invention relates generally to a magnetic head for use with magnetic reproducing equipment. More particularly, the magnetic head has a plurality of magneto-electric converting elements, for example, Hall elements, in a film form and a plurality of leads or terminals for providing electrical connections to an external circuit. The head also includes plural leads or terminals for use during the manufacturing process.
2. Description of the Prior Art
In the manufacturing of prior art magnetic heads of the ring core type, which is the most popular type, the front surface of the magnetic head is ground while the impedance of the head coil is measured, and the amount of head material ground off or removed is indicated by the measured impedance value. However, this method cannot be adapted to the manufacturing of a magnetic module head including semiconductor elements, such as Hall elements for example, instead of coils. In the manufacturing of such a semiconductor-type module head, the front surface of the magnetic head must be ground while the amount of material being removed is being measured, and the amount of material to be ground off is determined by the distance between the front edge of a substrate and the front edge of the semiconductor element formed on the substrate.
In the prior mass production processes for semiconductor-type heads, each substrate which comprises one half of the final head construction is manufactured to be of uniform size. One or more magneto-electric converting elements are uniformly formed in film form by vacuum deposition onto each substrate. The electric leads for the elements are formed onto each substrate by evaporating a metal thereon. One or more magnetic circuit elements, for example, a plurality of ferrite tips which will comprise the other half of the head constructions, are attached firmly to each substrate to correspond with each element; and by these steps, the fundamental construction of a head is accomplished. Then the front surface of the head must be ground to a predesigned uniform size. However, the distances between the front surface of the head and the front edges of each of the elements are not always identical. Consequently, heads manufactured in the manner described have uneven characteristics relative to each other; that is, the reproducibility factor of the prior art process for producing a plurality of uniform heads is low.
In another advanced prior art mass production process for semiconductor-type heads as disclosed in U.S. Pat. No. 3,787,638, one or more detector leads are provided which are used when the magnetic head is manufactured for measuring the amount of head material ground away from between a front surface of the magnetic head and the front edge of the magneto-electric converting element. According to this process, many improvements over the above mentioned prior art can be obtained; for example, by measuring the resistance of the detector leads, the grinding process becomes simple, and magnetic heads of the same characteristic are easily reproduced in large quantities. Namely, the front surface of the magnetic head is ground until the detector lead is ground away and electrically separated, whereby the amount of grinding can be accurately controlled. However, the grinding speed must be constant and low because it cannot be predicted when the detector lead will be electrically cut away. This raises problems when it is necessary to grind a large amount. Therefore, the time required for grinding becomes extremely long. If the grinding is done speedily, the material being ground which is usually composed of ferrite is chipped and the front surface of the magnetic head becomes coarse.